This invention relates to explosives having powdered ferrite magnet, or megnetized ferrite powder, as a tracer and a method for producing the same, and in particular, to improvements of powdered ferrite magnet dispersed in explosives.
In a Japanese patent application No. 45,858/'75 filed on Apr. 17, 1975 which was laid open for public inspection on Oct. 23, 1976 under No. 121,507/'76, two of three joint inventors of this invention, Ishii and Matsunaga, proposed, together with other joint inventor, an explosive in which powdered magnet is mixed and dispersed as a tracer.
Because the explosive having the powdered magnet can be detected by use of a magnetic detector, detection of a misfired explosive remained in the blasting hole or mixed with a muck, detection of a lost explosive, detection of illegal possession of an explosive, and detection of theft of an explosive cann be readily effected.
In case ferrite magnet is used as the powdered magnet dispersed in the explosive, it was found out that the explosive was subjected to chemical change during a storage. For example, the heat resistance of an ammonia gelatine dynamite (Enoki No. 2 dynamite) having the ferrite powder was measured 8-9 minutes according to Abel heat test. It was estimated that such a chemical change of the explosive was caused due to the existence of a certain alkaline material as a impurity in the powdered ferrite magnet. The alkaline material reacts on nitroglycerine, nitroglycol and/or nitrocellulose and accelerates decomposition of these ingredients of the explosive, so that the stability of the explosive may be degraded.